The present invention relates to an apparatus used in the E-Gun evaporating process, and more specifically, to a wafer loading/unloading apparatus for loading/unloading the wafer into/from the clamp ring of the E-gun evaporator.
In the semiconductor manufacturing industry, the electron beam evaporation (E-Gun evaporation) technique is widely used and was developed to overcome several known problems in the deposition of the aluminum layer, the nickel layer, the silver layer and other metal materials. This system provides several advantages over known technology. First, the evaporation process has a faster rate to deposit the required metal films. Second, the damage occurring on the wafer surface are not severe after performing the evaporating steps because the collision energy of the metal atoms is lower in the evaporating procedure. In addition, the incorporation of other gases into the deposited films can be prevent effectively because the evaporating procedure is usually done in a vacuum environment. Thus, the purity of the deposited metal films can be promoted considerably. Except for the released thermal energy from the condensation of the deposited films, only the heat radiation from the evaporating source will cause the temperature of the wafer to rise in performing the evaporating procedure. Therefore, the temperature of the wafer can be controlled accurately by using the evaporation process to form the metal films.
Referring to FIG. 1, the reactive chamber 10 of the electron-gun evaporator (E-Gun) for depositing metal films on the backside of the wafer is illustrated. Three planetary fixtures 20 with dish shapes are mounted on the chamber 10 for holding the wafers to perform the evaporating procedure. The shafts 28 and the edges of the planetary fixtures 20 are guided and rolled on the first circle rail 24 and the second circle rail 22 respectively. Namely, the planetary fixtures 20 can be rolled along the first circle rail 24 and the second circle rail 22 during the evaporating procedure. Besides, as shown in FIG. 1, the wafers can be mounted and fixed on the apertures 26 on the planetary fixtures 20 for depositing metal films onto the backsides of the wafers.
In general, the evaporating source (not shown in FIG. 1) is placed in a refractory crucible, and the refractory crucible is located on the bottom of the chamber 10. Then, the evaporating source is heated by the electron beam until the temperature is raised to the melting point of the evaporating source. The solid source will be evaporated to form the evaporating source atoms, and are deposited on the surface of the wafers above the source to form the metal films. The planetary fixtures 20 will be rotated along the directions of the central vertical axis 15, and the wafers (not shown in FIG. 1) mounted on the planetary fixtures 20 will be rolled along the directions of the shafts 28 of the planetary fixtures 20. Thus, the films formed on the wafer will have a uniform thickness.
Referring to FIG. 2, the method of mounting the wafer 34 onto the planetary fixtures 20 is illustrated. The wafer 34 is put into a clamp ring 30 first, and a top lid 32 is used to cover the wafer 34 and the clamp ring 30. Then, the clamp ring 30 is mounted into the aperture 26 on the planetary fixture 20 to perform the evaporating procedure. It is noted that the clamp ring 30 has a concave shape, and a hole 36 is formed on the central portion of the clamp ring 30 for exposing the backside of the wafer 34.
Referring to FIG. 3, however, it is not convenient to load the wafer 34 into the concave shaped clamp ring 30 by using a vacuum chucking pen 38 to transit the wafer 34. As shown in FIG. 3, the vacuum chucking pen 38 is tilted firstly at an angle to make the wafer 34 which is held by the vacuum chucking pen 38 in contact with the clamp ring 30. Then, the operator uses fingers to touch and shift the wafer 34 slightly into the clamp ring 30, and until then take the vacuum chucking pen 38 out of the clamp ring 30.
Similarly, after the evaporating procedure is performed, the vacuum chucking pen 38 cannot contact and suck directly the front side (upper surface) of the wafer 34 because there are various devices manufactured on the front side of the wafer 34. Thus the operator will usually have to touch the backside of the wafer 34 from the hole 36 (as shown in 10FIG. 2) of the clamp ring 30 and prop up the wafer 34 to make the edge portion of the wafer 34 out of the clamp ring 30. Then the vacuum chucking, pen 38 is stretched into the clamp ring 30 for sucking the backside of the wafer 34. Alternatively, the whole clamp ring 30 can also be overturned to let the wafer 34 pour down for unloading the wafer 34 out of the clamp ring 30.
However, whether propping up the wafer 34 by fingers to unload the wafer 34 from the clamp ring 30 or turning the clamp ring 30 upside down to pour down the wafer 34, the wafer 34 usually suffers from the damage such as being cracked or scratched, and this causes a considerable decrease in the yield and performance of the product. So there is still a requirement to have a wafer load/unload apparatus for loading the wafer into the clamp ring or unloading the wafer out of the clamp ring.
The object of the present invention is to provide a wafer load/unload apparatus for loading the wafer into the clamp ring for performing the evaporating procedure and for unloading the wafer after the evaporating procedure is done.
A wafer load/unload apparatus used to load/unload the wafer into/from the clamp ring for performing the E-Gun evaporation process is disclosed in the present invention. The apparatus comprises a base, a central cylinder and a plurality of peripheral cylinders. The base has an even upper surface, the central cylinder is connected to the upper surface of the base, and the plurality of the peripheral cylinders are connected to the upper surface of the base and are located around the central cylinder. A recessed trench penetrating through sidewalls of the central cylinder is formed on a top surface of the central cylinder. It is noted that the central cylinder can penetrate through a clamp ring, wherein the clamp ring is used to load a wafer for performing the E-Gun evaporating process. The spacing distances between the plurality of peripheral cylinders and the central cylinder are bigger than the width of the clamp ring. The plurality of peripheral cylinders are used to prevent the wafer placed on the top surface of the central cylinder from falling down. It is noted that when loading the wafer into the clamp ring, the clamp ring is first moved downward to hoop the central cylinder and is placed on the upper surface of the base. A vacuum chucking pen attached on a lower surface of the wafer for loading the wafer is then stretched into the recessed trench to transit the wafer onto the top surface of the central cylinder. The clamp ring is next moved upwards to load the wafer which is placed on the top surface of the central cylinder, after the vacuum chucking pen is removed. When unloading the wafer from the clamp ring, the clamp ring containing the wafer is moved downward to hoop the central cylinder and is placed on the upper surface of the base to remain the wafer on the top surface of the central cylinder.